Electrical condenser and method of making it



F. KRATZ.

ELECTRICAL CONDENSER AND METHOD OF MAKING IT.

APPLICATION FILED 1AN.26. 1917.

1,385,379. v Patented July 26, 1921.

19 I anvewto z fig 4.

Fran 163/2 $5 f Quorum UNITEDSTATES PATENT OFFICE.

FRANZ KBA'IZ, OF STUT'IGABT, GERMANY, ASSIGNOR, BY MESNE ASSIGNMENTS, T- AMERICAN BOSCH KAGNE'IO CORPORATION, OF NEW YORK, N. Y., A CORPORATION a 01' NEW YORK.

-EIEC'I .'BIOAD CONDENSER AND METHOD OF MAKING I'I.

To all whom it may concern:

Be it known that I, FRANZ KRATZ, a sub ject ofv the Emperor of Germany, residing at Stuttgart, Germany, have invented certain new and useful Improvements in Electrical Condensers and Methods of Making Them; and I do hereby declare the following to be a full, clear, and exact description of the invention such as will enable others skilled in the art to which it appertains to make and use the same.

The present invention relates to electrical condensers and methods of making them, and it is a continuation in art, of my copending application Serial 0. 815,47 8, filed anuary 30, 1914, now Patent No. 1,221,998, issued April 10, 1917.

Inasmuch as plate condensers are poorly adapted for manufacture by machinery, coll condensers made b winding two bands of conductive materia as metal foil, with insulation between, have been proposed. When the terminals of such condensers are formed by the end portions of the bands of foil, the wires, metal bands or the like, connected to the ends of the bands of foil, may tear oil? at the place of attachment. Furthermore, the electrical resistance of the bands of foil depends upon the length of the bands, and if the band is ruptured in winding the condenser, only those portions of the bands between the place of rupture and the connecting wires are effective for the purose. p In accordance with my invention, these disadvantages are obviated, and not only is an improved product obtained, but the methods herein disclosed are nicely applicable for economical manufacture of large quantities of such condensers. In these methods, the two conductive bands are wound in such manner that at least one, and preferably both of them project laterally on the individual sides 0 Preferabl the insulation between adjacent bands of oil is in the form of two bands or ribbons of insulating material such as paper, and these insulating bands are wound simultaneously with the conductive bands, the insulating bands being of such width and so laterally displaced as to extend laterally of the overlapped ortions of the bands of foil. In this way, t e sidewise projecting edge portions of the entire length of one of the Specification of Letters Patent.

the condenser.

Patented July 26, 1921.

Application filed January 26, 1917. Serial No. 144,846.

bands of foil is exposed on one side of the condenser, while the sidewise projecting edge portlon of the other band of foil is exposed on the other side of the condenser. These sidewise projecting edge portions are then turned over to form side terminals for the condenser, and when turned over they provide substantially continuous contact surface capable of effecting intimate contact throughout the entire length of the bands of foil, with a plate or other suitable form of circuit connection. Thus the electrical resistance of the condenser is decreased, the effect of a rupture in either or both bands of 011 1s of no consequence, and the character of the contact between the terminals of the condenser and the circuit connection is improved.

In some applications, it is desirable that the condenser have an oval shape instead of a round shape. Formerly, the oval shape has been produced by winding the bands on a round or other sha ed core and then pressmg the wound con enser to the desired shape after the core has been removed.

However, this subsequent compression is apt to strain the bands at the places of lesser radius, and attempts have been made to obviate this effect either by loosely winding the coil so as to provide accommodation for the subse uent change of shape, or the condenser has en. wound on a core of comparatively large diameter. In both cases the capacity of a condenser of this kind is comparatively small for the volume which it occupies. In accordance with the method disclosed herein for producing coil condensers of oval shape, the bands are wound part such as the armature of an ignition current generator.

The accompanying drawings illustrate the 10 a wound condenser, with the sidewise projecting band of foil turned over on one side only against the condenser by a terminal plate; and Fig. is an enlarged view, partly broken away, showing the turned over edge portions of the bands of foil.

Figs. 1 and 3 show the method of winding the condenser, in which the coils of two conductive bands of metal foil are insulated from each other by two bands of paper. In both arrangements, the rotatable s indle 3 is surrounded by an insulating s eeve 12 forming the core for the condenser. In Fig. 1 the core 12 is of oval shape, so as to form an oval condenser directly, that is, without subsequent compre$ion or baking, while in Fig. 3 the core 12 is round, so as to produce a round condenser. The spools 4 and 5 carrying the bands of metal foil are arranged on opposite sides of the core 12 with their axes parallel to the axis of'the core. The conductive band on spool 4 is slightly offset to one side, while the other conductive band on spool 5 is slightly offset to the other side. The spools 6 and 7 carry the two bands of paper to form the insulating material between the conductive bands and are arranged on opposite sides of the core 12 so as to lie between adjacent coils of the conductive bands. The bands of paper are of lesser width than those of the bands of foil and are arranged to overlap without extending to either outside edge of the foil, as is best shown in Fig. 2. Thus, as the spindle 3 is rotated, there is simultaneousl wound on the core 12 a layer of metal foi for instance, the conductive band 1, a layer of paper, as 8, a layer of the second conductive band 2, and a layer of the second paper band 9. The conductive band 1 pro'ects throughout its entire length on one si e of the condenser, while the conductive band 2 projects throughout its entire length on the other side of the condenser, the bands 8 and 9 of insulating material extending on each side slightly beyond the overla ped portions of the conductive bands, there y providing sidewise projecting portions 1 and 2" of foil on the individual sides of the condenser. The pressure rolls 10 and 11 are arranged to compact and solidify the condenser as the bands are beingwound on the core, and these pressure rolls are so arranged that they accommodate the condenser of either an oval or a round shape as the bands are wound on the. core.

A condenser wound in this way, on either a round or oval core, has the edge portions '1 and 2 projecting laterally on opposite sides, and the edge portions project to such an extent that when turned over substantially against the sides of the wound condenser, they form side terminals therefor having substantially continuous contact surfaces, as shown in Fig. 5. The projecting edge portions may be turned over by plates pressed against the sides of the wound condenser, as indicated in Fig. 4, or in any other suitable way. The contact surfaces provide effective connection with the entire length of the bands of foil, when the side plates or other suitable conducting pieces are pressed against the sides of the condenser. In this way a connection is made the entire length of both bands of foil, and besides reducing the electrical resistanceof the condenser, the contact surface is increased and the effect of a break at any place in either band of foil is entirely nullified.

Having thus described my invention, what I claim is:

' 1. The method of making electrical condensers, which consists in simultaneously winding alternate bands of foil and dielectric laterally displaced in such manner that one of the bands of foil projects on one side of the bands of dielectric to form a narrow projecting edge portion, and then pressing the projecting edge portion flat against the side of the condenser to form a side terminal, the narrow projecting edge portion being of such width as to form a substantially continuous contact surface on the side of the condenser when pressed flat thereagainst.

2. The method of making electrical con- 105 densers, which consists in simultaneously winding alternate bands of foil and dielectric laterally displaced in such manner thatthe individual bands of foil project on opposite sides of the bands of dielectric to form nar- 110 row projecting edge portions, and then pressing the pro'ecting edge portions flat against the sides 0 the condenser to form side terminals, the narrow projecting edge portions being of such width as to form substantially 115 continuous contact surfaces on the sides of the condenser when pressed flat thereagainst.

3. The method of making electrical condensers, which consists in simultaneously winding alternate bands of foil and dielec- 120 tric laterally displaced in such manner that the individual bands of foil project on opposite sides of the bands of dielectric to form narrow projecting edge portions, subjecting the condenserto pressure as the bands are be- 125 ing wound thereon, and pressing the projecting edge portions fiat against the sides of the condenser to form side terminals, the narrow projecting edge portions being of such width as to form substantially continuous 130 contact surfaces on the sides of the condenser-when ress'ed flat thereagainst.

4; The method of making electrical condensers, which consists in simultaneously winding on an oval. core alternate bands of foil and dielectric laterally isplaced in such manner that the individua bands of foil project on opposite sides of the bands of dielectric to form narrow projecting portions, and then pressing the pro ecting edge portions flat against the sides of the condenser to form side terminals, the narrow projectin edge portions being of such width as to orm substantially continuous contact surfaces on the sides of the condenser when pressed flat thereagainst.

5. The method of making-electrical condensers, which consists in simultaneously winding on an oval core alternate bands of foil and dielectric laterally dis lacedin such manner that the individual ands of foil project on opposite sides of the dielectric to form narrow projecting edge portions, sub- ,wjecting the condenser to pressure as the bands are being wound theron, and then pressing the against the sides of the condenser to form terminals, the narrow projecting edge ,portions being of such width as to form'substantially' continuous contact surfaces oxfthe sides of the condenser when pressed flat thereagainst.

6. An electrical condenser having alter-- nate bands of foil and dielectric, one of the edge ,nate bands of foil and dielectric, the indithe con being of suchwidt projecting edge portions fiat bands of foil having 'a narrow laterallyprojecting edge portlon ling substantially flat against the sideofthe condenser "and forming a side terminal therefor, the narrow projecting edge, portion beingof such width as to form a substantiall continuous contact surface on the side of th when pressed flat thereagainst. a

An electrical condenser having altervidual bands of the foil having narrow laterally-projecting, edge portions lying -sub-' stantiall flat against'the opposite sides of (l enser to .form' for, the narrow rojecting edge portions ll as to form substantially continuous contact surfaces on the sides' of the condenser when pressed flat there! against.

e condenser side terminals there- 8. An electrical condenser having an oval,

core, and alternate bands of foil and dielec-' trio wound thereon, the individual bands of foil having narrow laterally-projecting edge portions lyingsubstantially flat agai t td opposite sides of the condenser to fo terminals therefor, the narrow projecting edge portions being of such width FRANZ KRATZ;

so as to form i substantially continuous contact surfaces on 

